<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var year= prompt('请输入年份');
        if (year%4==0 && year%100!=0 || year%400==0) {
            alert('闰年')
        } else {
            alert('平年')
        }
    </script>
</body>
</html>